Abstract

The bacterial microflora present and its relationship with Xanthomonas campestris pv. phaseoli (Xcp) were studied in bean seeds, on 118 genotypes coming from VIDAC - 98, INTA - Nicaragua, TARS - USDA and Isabela - P.R. Five isolation methods were used: seed decontaminated with sodium hypochlorite, seed treated with refrigerated nutrient broth for one hour, dispersion of 0.1 ml of suspension of seeds between solid, liquid sowing of 1 ml suspension and seed in nutritious, agitated broth and refrigerated by 24 hours. One hundred and four yellow colonies from 41 genotypes were isolated. Thirty-six colonies were positive KOH (Gram negative), 68 negative (Gram positive) and 34 were starch hydrolyzers. The yellow colonies were nonpathogenic under greenhouse conditions. These were identified with the BIOLOG system as: Pantoea agglomerans (25), Xanthomonas campestris (2), Enterobacter agglomerans (2), Sphingomonas paucimobilis (2), Pseudomonas fluorescens and Flavimonas oryzihabitans. In addition, the genotypes carried colonies with other pigmentations. Antagonistic colonies were identified with deoxyribonuclease activity and antibiosis to Xcp. Of these, 15 colonies inhibited Xcp significantly. The fungi were identified as: Rhizoctonia solani, Penicillium spp., Fusarium spp., Aspergillus flavus, Rhizopus nigricans and Macrophomina phaseolina in 52.9% of the total evaluated genotypes.